You are getting confused by Ruby's syntactic sugar (which Rails uses profusely). Let me explain this briefly before answering your question.
When a ruby function takes a single parameter that is a hash:
def foo(options)
#options is a hash with parameters inside
end
You can 'forget' to put the parenthesis/brackets, and call it like this:
foo :param => value, param2 => value
Ruby will fill out the blanks and understand that what you are trying to accomplish is this:
foo({param => value, param2 => value})
Now, to your question: link_to
takes two optional hashes - one is called options
and the other html_options
. You can imagine it defined like this (this is an approximation, it is much more complex)
def link_to(name, options, html_options)
...
end
Now, if you invoke it this way:
link_to 'Comments', :name => 'Comments'
Ruby will get a little confused. It will try to "fill out the blanks" for you, but incorrectly:
link_to('Comments', {:name => 'Comments'}, {}) # incorrect
It will think that name => 'Comments'
part belongs to options, not to html_options
!
You have to help ruby by filling up the blanks yourself. Put all the parenthesis in place and it will behave as expected:
link_to('Comments', {}, {:name => 'Comments'}) # correct
You can actually remove the last set of brackets if you want:
link_to("Comments", {}, :name => "comments") # also correct
In order to use html_options, you must leave the first set of brackets, though. For example, you will need to do this for a link with confirmation message and name:
link_to("Comments", {:confirm => 'Sure?'}, :name => "comments")
Other rails helpers have a similar construction (i.e. form_for
, collection_select
) so you should learn this technique. In doubt, just add all the parenthesis.